TOKYO – North Korea launched three missiles into the sea between the Korean Peninsula and Japan on Saturday morning, reigniting tensions after a month of heated rhetoric between Pyongyang and Washington and dispelling President Donald Trump's assertion that Kim Jong Un had come to "respect" him.

The missiles appeared to be short-range, not the intercontinental ones capable of reaching the mainland United States that North Korea fired last month, and all quickly failed.

Still, the latest launches underscore Kim's continued focus on making strides in his weapons program and his continued defiance of international calls for him to desist.

Analysts said the launches appeared to be a response to the ongoing joint exercises between the United States and South Korean militaries, exercises that North Korea always strongly protests because it considers them preparation for an invasion.

Furthermore, South Korea fired three missiles of its own this week.

"When they (North Korea) fire salvos of missiles, it's usually because they're training, so in a way, they're doing their own exercises," said Melissa Hanham of the Center for Nonproliferation Studies in California.

Kim had just supervised a special forces target-striking contest, practicing attacks on two South Korean islands, the North's state-run Korean Central News Agency reported separately Saturday.

The North Korean People's Army "should think of mercilessly wiping out the enemy with arms only and occupying Seoul at one go and the southern half of Korea," Kim told his special forces, KCNA reported.

Saturday's salvo was composed of three short-range missiles fired over the course of half an hour from Kittaeryong on North Korea's east coast, according to the U.S. Pacific Command in Hawaii.

The first and third missiles failed in flight, while the second appears to have blown up almost immediately.

"We are working with our interagency partners on a more detailed assessment and we will provide a public update if warranted," Cmdr. Dave Benham, a spokesman for the U.S. Pacific Command, said in a statement. The missiles did not pose a threat to the United States, he added.

The White House said that the president had been briefed on the launches and that it was monitoring the situation.

South Korea's Joint Chiefs of Staff said they were working to determine the types of missiles fired, which they said traveled only 150 miles before falling into the sea. South Korea's national security council convened to discuss the latest provocations.

The launches puzzled analysts because North Korea does not typically have problems with tried and tested short-range missiles like Scuds.

Even though the launches failed, they still constitute violations of the U.N. Security Council resolutions prohibiting North Korea from launching missiles or conducting nuclear tests, and they will spark another round of condemnation from the international community – condemnation that will, again, fall on deaf ears in Pyongyang.

The latest launches came as the Trump administration, after a month of threatening to unleash military "fire and fury," expressed hope that the North Korean regime was curtailing its provocations.

At a campaign rally this week, Trump said that Kim "is starting to respect us" and that maybe "something positive can come about."

This echoed an earlier remark from Secretary of State Rex Tillerson that "Pyongyang has certainly demonstrated some level of restraint that we've not seen in the past."

The latest salvo appeared to be a rebuttal to that assessment but also a direct response to the Ulchi Freedom Guardian exercises that are taking place in South Korea until Aug. 31.

Those exercises, which mainly involve computer simulations rather than battlefield maneuvers or flyovers with bombers, are smaller than usual this year, with 17,500 American troops participating, down from 25,000 last year.

China and Russia had been calling on the United States to scale back the exercises, but the Pentagon said the decrease in troops was due to operational reasons, rather than to tamp down tensions on the Korean Peninsula.

North Korea has still issued angry statements about the exercises, saying most recently that they were evidence that the United States planned to invade the country. The United States and its "puppets" in South Korea should "act with discretion if they want to evade the historic moment of death," KCNA reported.

Kim has been aggressively pursuing more advanced missile technology, and North Korea has now conducted 17 launches so far this year. By comparison, his father, Kim Jong Il, presided over only 16 missile launches during 17 years in power.

Most alarmingly, North Korea last month fired its first intercontinental ballistic missiles, which are technically capable of reaching the mainland United States.

As tensions increased this month, Kim's regime warned that it was considering launching missiles into the Pacific Ocean near the U.S. territory of Guam, prompting Trump's warning that the U.S. military was "locked and loaded" and ready to retaliate.

Kim has not been deterred.

This week he visited the Chemical Material Institute of North Korea's Academy of Defense Sciences and inspected designs for two new longer-range missiles, according to state media reports. The new and untested designs, labeled as the Pukguksong-3 and the Hwasong-13, appear to be for new types of intercontinental ballistic missiles.

The ICBMs that North Korea fired last month were theoretically capable of reaching Denver and Chicago, a development that has alarmed policymakers but which nonproliferation experts say is clearly in line with Kim's stated aims.